Spine and Human Anatomy: Questions & Answers

How long do human body cells live?
It depends on the type of cell. Some cells live longer than others. Bone cells can last years. In healthy bones, cells that die are replaced. Millions of red blood cells die each minute, but are quickly replaced. Nerve cells are the only cells that are not replaced.

What type of tissue is in the body?
There is nerve and muscle tissue, plus other types. Connective tissue holds - connects - other tissues together. Epithelial (ep-eye-thee-lee-all) tissue is layered covering the body and lines many body cavities.

What are extremities?
Extremities (x-trem-it-tees) are arms, legs, hands, and feet.

How long is the spinal cord?
In an average adult, the cord is about 18 inches long.

How many ribs do people have?
Most people have 12 on each side - a total of 24 ribs. The ribs are part of the thoracic spine and make up what is called the "rib cage." See picture below.

Posterior (Rear) Spine & Rib Cage

What is the name of the first vertebra?
The first vertebra is located in the cervical (neck) spine. It is called the Atlas. It helps to support the weight of the head. It got its name from Greek mythology in which, according to the legend, a man named Atlas was forced by the gods to support the pillars separating Heaven from Earth.

How much do all the muscles in the body weigh?
The total muscle weight depends on how much the person's entire body weighs. Muscles make up about 40% of a person's total body weight. For example, the muscles of a person weighing 100 pounds would weigh about 40 pounds.

How does smoking affect the body?
Cigarettes, cigars, pipe tobacco and other tobacco products contain hundreds of poisons. Nicotine is a very poisonous substance in tobacco smoke. Carbon monoxide is a poisonous gas found in cigarette smoke. Smoking raises blood pressure, reduces the amount of oxygen in blood, causes mucus to build up in the lungs, and can cause death. People who smoke get sick more often and heal slower than non-smokers.